38
39
39. Signalling,
A candidate must be able to-
(1) send and receive morse at the rate of 4 words per minute;
(2) recognize the flags of the International Code and know the meaning
of the following single fag urgent and important signals-
AD‚FELOR,U,V.
PART II.
A. COMPASS DEVIATION,
(a) Magnetism,
40. Candidates will be required to show full knowledge of the subject referred to in sub-paragraph (1) of paragraph 21, and paragraph 25 of this Schedule and will, in addition, be required to answer questions calling for a knowledge of the following
(1) Magnetic properties of materials, induction, susceptibility and permea- bility. Magnetic cffects of electric currents, including calculations.
(2) Terrestrial magnetism. Dip, total force, horizontal force and vertical force. Effects on the deviation of the compass accompanying change in the values of these elements. Variation.
(3) Ship's magnetiam. Hard and soft iron. Permanent, subpermanent and induced magnetism. Components P.Q.R, the roda a, b, c, d, e, f, g, b. k. The approximate coefficients A, B, C, D, E, Heeling Error. Lambda, Lambula mo and Mu.
(4) General principles of compass correction Methods of finding and compensating a compass for the various components which might cause deviation, including the effects of heel sad trim.
(5) Compensation by use of the Kelvin deflector. Principle of the deflector tretbod and information which can be deduced from readings obtained.
(6) The siting and lining up of compasses with due regard to the proximity of magnetic material, electrical devices and other disturbing influences.
(7) The theory of degaussing in ships fitted with M colls and compass compensation by means of B and heeling stror coils.
(8) Swinging ship and the analysis of a deviation tablo.
(b) Electricity.
41. Candidates will be expected to show full knowledge of the subjects referred to in sub-paragraph (2) of paragraph 21 and sub-paragraph (2) of paragraph 28 of this Schedule and will, in addition, be required to answer questions calling for a knowledge of the following —
(1) D.C. Circuits.
(a) Kirchoff's Laws and their applications.
(6) Measurement of resistance by simple bridge method. Principle of
Megger and it ONE.
(c) Principles of Electrolysis; concept of the principles of Cathodic
Protection.
(4) A qualitative treatment of the effect of inductance in a D.C. circuit (2) A qualitative treatment of the charge and discharge of a condensor is
a resistive circuit
(2) D.C. Motors and Generators.
(a) Simple relationships between speed, fold-strength induced stuf, armature current and torque. Behaviour of shunt, series and compound- wound machines. The concept of power losses in a machino; efficiency. Simple starter for D.C. sbunf-wound motor. Voltage control of shunt- wound dynamo.
(b) The magnetic relay as exemplified to simple shunt motor starter with
no-volt and overload rakases,
(3) AC Motors and Generators.
The principles of rotating armature, rotating field and inductor type generators and induction motors.
(0) AC Circuits.
(a) Peak, Average and Root Mean Square values of sinusoidal alternating
voltages and currents.
(8) A quantitative treatment of the effect of resistance, inductance and
capacitance in a series A.C. circuit; reactance.
(c) Simple examples of vector treatment of combinations of resistance, inductance and/or capacitance in a series A.C. Circuit; impedance:
resonance.
(d) Power in an A.C. circuit; power factor.
(5) High Frequency Circuits.
(a) The fundamental principles of heterodyne and superheterodyne reception. (6) Principles of suppression of radio interference from electrical equipment, (c) An elementary knowledge of the principles of directional aerials. The interpretation of the horizontal polar diagram, as excmplified in the case of the simple loop acrial and radar aerial.
(d) A concept of the meaning of the term "Aerial Cain” and a knowledge of the use of the decibel as a unit used in the measurement of relative power.
(e) The capses of fixed and variable errors to which navigational alds, used
in British ships, are subject.
B. SPECIAL SIGNALLING.
42. The examination in Signalling will in all cases begin with an examina- tion in the International Code, including Morse Flashing and Semaphore.
43. Morse Flashing and Semaphore.
(1) Candidates for the examination will be required to attain a minimum speed of 12 words a minute in Semaphore and 10 words a minute in Morse Cushing; the average length of a word is taken as 5 letters.
(2) The Morse fashing test will consist of a Test message, followed by a Spelling message of 25 words, and the Semaphore test will consist of a Spelling Message of 50 words.
(3) In the examination in Morse flashing, the candidate will first be required make a Test message, followed by a Spelling message of 25 words. The caminer will then make a Test massage, followed by a Spelling message of 25 words to be read by the candidate.
(4) The same procedure will be observed in the Semaphore test, except that, as a Test message is not given, the candidate will be required to make a Spelling message of 50 words, and then to read a message of 50 words made by the examiner.
(5) Candidates will be thoroughly tested in the various signs and the procedure of calling up, sending and answering a signal.